I have a 450L South American set-up, heavily planted with bits of bogwood and a few flat stones on a sand substrate. It's got a shoal of 30 cardinal tetras, 10 sterbai cory, 4 ottos and some red cherry shrimps. My question is would a pencilfish species inhabit the top layers of the water, or would I be better off with a group of hatchetfish? There are three areas with floating plants, so there should be enough cover for either type of fish. If anyone has pencilfish - do they stay near the top and if so which species is it?

I've no experience of pencilfish but hatchets are amazing. These are my marbled hatchets, always scooting around the top of the tank and dashing through the filter flow or sitting still in formations that the Red Arrows would be proud of! Really give life to a part of the tank that was empty.

My six Nannostomus beckfordi ("Golden Pencilfish" ... despite being more of a reddy brown!) from MatsP on here spend a vast majority of their time very close to the water surface, amongst the floating plastic tubes that temporarily have various Anubias plants attached to them with elastic bands.

My six Nannostomus beckfordi ("Golden Pencilfish" ... despite being more of a reddy brown!) from MatsP on here spend a vast majority of their time very close to the water surface, amongst the floating plastic tubes that temporarily have various Anubias plants attached to them with elastic bands.

I take it they are doing OK, then? I was wondering... And yes, pencilfish in general are great little top-level fish. They will swim elsewhere, but they typically spend time at the surface, as long as there is a bit of shade and such.

Right wasn't really able to get a GOOD shot of my tank - glass not clean enough (yes, I can clean it, but wasn't going to do that for now) and I've just had a big rummage to get bristlenoses out of there, so a fair bit of "particles" floating about.

But here's one picture of the group that contain the parents of NOTG's fish:

I did get some decent photos of my Nannostomus marginatus in another tank:

Yep, they are still doing well, Mats, despite my worries about how they would adapt to Southampton's hard tap water from your RO setup... We regularly see spawning behaviour and mid week I may have seen a ~5mm wiggler for all of about two seconds!

What size are your oldest ones now, Mats... Getting anywhere near 6cm SL? Looks a great group in the photo and I'm green with envy at seeing some Barbus fasciolatus down the tank bottom, something I could almost certainly not risk without going down the route of at least a tap water/RO mix.

The barbs are all from Aqualife in Preston - I bought some from a Czech import, and they didn't last very long. Apparently a local breeder keeps supplying the shop. They are great, and I kept them in my tank with RO waste-water before I moved away from my now ex-wife, [and they went on "holiday" with a mutual friend of ours, Martin, for a few months as well, where he kept them in his local tap-water] so I don't think they are acidophiles of the extreme type, but they do colour up a bit nicer in the softer water.

Quick update - went for golden pencilfish and they do now occupy the top layers of the tank. The much bigger and more numerous Cardinals now stay at the bottom and do get chased by the pencilfish so don't roam around the tank like they used to but hide away in a fairly tight shoal.